Simulations of Interacting Binary Systems -- Pathways to Radio Bright GRB Progenitors

TL;DR

This study uses stellar evolution simulations to identify binary star configurations that can produce the high spin necessary for gamma-ray burst progenitors, focusing on the effects of tides, mass loss, and initial rotation.

Contribution

It provides a detailed analysis of how binary interactions influence stellar spin and mass loss, identifying parameter spaces conducive to GRB progenitors.

Findings

Tidal interactions can spin up massive stars in binaries, but late-stage expansion may cause tidal stripping.

Potential GRB progenitors exist in binaries with specific orbital periods and mass ratios, with sufficient stellar spin.

Initial stellar rotation and mass loss critically affect the final spin and black hole formation conditions.

Abstract

Although the association of gamma-ray bursts with massive stellar death is on firm footing, the nature of the progenitor system and the key ingredients required for a massive star to produce a gamma-ray burst remain open questions. Here, we investigate the evolution of a $15-25M_\odot$ massive star with a $10-15 M_\odot$ black hole using the MESA stellar evolution code. We quantify companion-influenced angular momentum evolution over stellar lifetime for orbital periods where tides are significant, varying stellar and black hole masses, initial stellar spin, and accretion and dynamo prescriptions while tracking mass loss and angular momentum. Final spin is set by tidal torques versus stellar winds. For binaries that initially avoid Roche lobe overflow, tides can spin up the star, but late stage expansion can drive tidal stripping; associated mass and angular momentum loss can suppress spin up. We find that massive star black hole binaries at comparable mass ratios may be potential GRB progenitors for short orbital periods ($\sim 20 - 5\times10^2$ days) and long orbital periods ($\sim 2\times10^3 - 4\times10^3$ days), where our suite of lifetime simulations reveals a favored parameter space with negligible mass loss and enough spin angular momentum to power a GRB jet. For initially non-rotating stars, this provides a lower limit on final spin above a threshold estimate consistent with forming a post collapse black hole mass of $5-10M_\odot$ with spin parameter $\geq 0.5$. For initially rapidly rotating stars, tidal interactions may sustain high spin when mass loss is negligible because the binary is not tidally synchronized.